TwoSum.py

import pytest


class Solution:
    def brute_force(self, numbers, target):  # numbers = [4, 8, 12, 13, 15, 18, 22] & 7 elements, target = 28
        for i in range(len(numbers) - 1):  # i = 0,1,2,3,4,5,6
            # for j in range(i+1): # it is a mistake because the end point is i so j stop till i only so we have to mention that start,end point in range
            for j in range(i + 1, len(numbers)):  # j = 1,2,3,4,5,6,7
                # print(f"i = {i}, j = {j}, {numbers[i]} + {numbers[j]} = {numbers[i] + numbers[j]}")
                if numbers[i] + numbers[j] == target:
                    return [i + 1, j + 1]

    def twosum(self, numbers, target):
        left = 0
        right = len(numbers) - 1
        while left < right:
            total = numbers[left] + numbers[right]
            if total == target:
                return [left + 1, right + 1]
            elif total > target:
                right -= 1
            else:
                left += 1


problem = Solution()

# ====================== TEST CASES (FIXED) ======================
test_data = [
    {"numbers": [2, 7, 11, 15], "target": 9, "expected": [1, 2]},
    {"numbers": [1, 3, 5, 7, 9], "target": 16, "expected": [4, 5]},  # 7 + 9
    {"numbers": [1, 4, 6, 8, 10], "target": 14, "expected": [2, 5]},  # 4 + 10
    {"numbers": [-10, -3, 0, 5, 9], "target": 6, "expected": [2, 5]},  # -3 + 9
    {"numbers": [-8, -5, -3, -1], "target": -9, "expected": [1, 4]},  # -8 + -1
    {"numbers": [1, 2, 2, 3, 4], "target": 4, "expected": [1, 4]},  # 1 + 3
    {"numbers": [1, 2], "target": 3, "expected": [1, 2]},
    {"numbers": [1, 5, 20, 35, 100], "target": 120, "expected": [3, 5]},  # 20 + 100
    {"numbers": [1, 2, 3, 4], "target": 20, "expected": None},  # No solution
    {"numbers": [0, 2, 4, 6, 8], "target": 8, "expected": [1, 5]},  # 0 + 8
    {"numbers": [3, 3, 4, 5], "target": 6, "expected": [1, 2]},  # 3 + 3
    {"numbers": [4, 8, 12, 13, 15, 18, 22], "target": 40, "expected": [6, 7]},  # 18 + 22
]
for idx, test in enumerate(test_data, start=1):
    numbers = test["numbers"]
    target = test["target"]

    print(f"\nTest Case {idx}")
    print(f"numbers = {numbers}")
    print(f"target = {target}")

    print("Brute Force:", problem.brute_force(numbers, target))
    print("Two Pointer:", problem.twosum(numbers, target))


@pytest.mark.parametrize(
    "numbers, target, expected",
    [(t["numbers"], t["target"], t["expected"]) for t in test_data],
)
def test_twosum_brute_force(numbers, target, expected):
    sol = Solution()
    result = sol.brute_force(numbers, target)
    assert result == expected


@pytest.mark.parametrize(
    "numbers, target, expected",
    [(t["numbers"], t["target"], t["expected"]) for t in test_data],
)
def test_twosum_twosum(numbers, target, expected):
    sol = Solution()
    result = sol.twosum(numbers, target)
    assert result == expected